I bought a Kern switar 10mm 1.6 lens on ebay. It didn't write "H16RX " as my other rx lenses.
However it is strange that it could focus correctly on both of my reflex and non reflex H16 cameras.
Is there anyone knows about more the version and usage of this lens?

The "RX" lenses include an aberration correction to account for the prisms in the "RX" bolex cameras-- if you are not using an RX bolex then you do not want the correction. That said, the effect is minimal and you may or may not care.

Well, my other two non reflex lens: yvar16mm 2.8 and switar 25mm 1.5 even couldn't be mounted on reflex body,
which means their rear elements go deeper to the mount than RX lenses, so I am in doubt that the old rx version of 10mm 1.6 doesn't have the "RX" written on the lens...